This galaxy is about to get the longest we’ve ever seen

300 million years after the Big Bang, the galaxy HD1 was already shining. The celestial object has just been discovered by scientists, at a distance of 13.5 billion light-years from us.

This galaxy shone in the universe nearly 300 million years after the Big Bang. Called HD1, this structure is described as the most distant astronomical object ever observed, in a press release from the Harvard-Smithsonian Center for Astrophysics on April 7, 2022.

Two teams of scientists worked on HD1, where their results had been accepted The Astrophysical Journal (ApJ) and Monthly announcements from the Royal Astronomical Society Letters (MRNAS). It should be noted that one of the co-authors of the second text is Abraham Loeb: this scientist is a recognized cosmologist (for his work on the study of the structure of the universe), but he is also the cause of dubious theories about the interstellar object Oumuamua (on despite not having specialized in the physics of the solar system). The theme addressed here is part of its original thesis.

What do we know about this galaxy so far away?

HD1 is located 13.5 billion light-years from us. The two teams of scientists wonder about its exact nature. The hypotheses mentioned are as follows:

  • The galaxy is said to form new stars at a fast speed. It may even contain population III stars. This hypothetical group would be the one of the very first stars formed at the beginning of the universe. But such stars have not yet been seen directly;
  • The galaxy could also contain a giant black hole 100 million times the mass of the Sun, which would make it a supermassive black hole.

Determining the characteristics of a galaxy so far away is complex. ” It’s like guessing a ship’s nationality based on the flag it’s sailing while it’s far ashore and the ship is trapped in the wind and thick fog. “, Compares Fabio Pacucci, astrophysicist at the Smithsonian Astrophysical Observatory, lead author of the article published in MNRAS and co-author of the article in ApJquoted in the press release.

The history of the universe and the formation of the first galaxies. // Source: Harikane et al., NASA, EST and P. Oesch / Yale

To study HD1, the researchers used more than 1,200 hours of observations made from several observatories: the Subaru Telescope (Hawaii), the VISTA Telescope (Chile) and the Spitzer Space Telescope (which have not been in operation since 2020). The giant ALMA radio telescope (Chile) was also mobilized to confirm the distance to HD1 and to verify that it was farther away than the previously known distant galaxy, GN-z11 (13.4 billion light-years).

It turns out that HD1 is sharp in ultraviolet light, suggesting that the galaxy must experience (or experienced a few billion years earlier) significant energetic processes. Scientists were also able to estimate that the galaxy forms more than 100 stars each year – 10 times more than expected for such a galaxy. It is for this reason that there is a suspicion that HD1 may not form normal stars, but population III stars … which are thought to be able to emit more ultraviolet light than others.

Further

Hubble in 1997. // Source: Flickr / CC / Nasa (cropped photo)

But the hypothesis of black hole is not to be ruled out because it could completely swallow gas in large quantities and also explain the brilliance of HD1. Confirming the presence of such a black hole in this galaxy would be historic because then it would be the first black hole known and observed so soon after the Big Bang.

The James Webb Telescope, which will soon be ready for its scientific observations in space, should help verify the distance between HD1 and our planet and possibly confirm that this galaxy is the oldest ever discovered.

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